[IA64] Add ptc.l emulation

[IA64] Add ptc.l emulation

This patch adds support for ptc.l emulation for xenlinux.
In 2.6.16 kernel it flush_tlb_range will call global_tlb_purge
directly, so ptc.l shouldn't be used when CONFIG_SMP enable.
But in order to enhance performance (maybe), 2.6.17 kernel in
smp environment will do mm check first. If mm is current->active_mm
and the mm (corresponding process) just runs on the local processor,
kernel only needs to do ptc.l at local processor instead of global purge.
So ptc.l emulation is necessary for 2.6.17 kernel.

Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>